diff --git a/src/libecoPCR/ecotax.c b/src/libecoPCR/ecotax.c
index 4da5142..813c490 100644
--- a/src/libecoPCR/ecotax.c
+++ b/src/libecoPCR/ecotax.c
@@ -208,12 +208,13 @@ int eco_isundertaxon(ecotx_t *taxon,
 	ecotx_t *next_parent;
 	
 	next_parent = taxon->parent;	
-		
-	while ( (other_taxid != next_parent->taxid) && (next_parent!=0) )
+	
+	while ( (other_taxid != next_parent->taxid) && 
+			(strcmp(next_parent->name, "root")) )
 	{
 		next_parent = next_parent->parent;
 	}
-	
+		
 	if (other_taxid == next_parent->taxid)
 		return 1;
 	else